OLED display panels have many advantages such as active light emitting, high contrast ratio and having no limitations on view angle over many other display devices. Particularly, flexible OLED display panels are even more advantageous. Flexible OLED display panels are slimmer in volume and lower in power consumption than the devices in the prior, which may facilitate the improvement of the battery life of the device. Meanwhile, based on the characteristics of bendable and good flexibility, its durability is greatly improved over the existing screens, and thus the risk of accidental damage to the device may be reduced. Therefore, flexible OLED display panels have been wildly used in the art of display technology, and will become a mainstream of further OLED display consumption. However, lifespan of OLED elements in the flexible OLED display panel is an important development bottleneck thereof. Accordingly, well water and oxygen resistance of the thin film encapsulation is particularly important to the flexible OLED display panel.
Thin film encapsulation (TFE) process of an organic electroluminescent diode is used in the encapsulation process of flexible OLED display panel, which may improve the encapsulation performance as well as the mechanical performance of the flexible OLED display panel by alternatively depositing plating films between inorganic layers and organic layers. In an example, a thin film without pinhole and with good compactness may be formed by atomic layer deposition (ALD) in the TFE process. Generally, a thin film deposited to a thickness of 50 nm may have a water vapor transmission rate (WVTR) up to 103 g/m2·24 h. However, the ALD has a serious plating film diffusion effect, and if it is not blocked effectively, it may directly contact moisture and react slightly with water to form aluminum salts. In turn, peripheral water and oxygen resistance of the OLED device and thus encapsulation effect of the flexible OLED display panel may be decreased.
In the prior art, a bank layer having a shape of continuous strip shape is generally used to block the diffusion effect of the ALD. However, while developing the flexible OLED display technology, the bank layer may bear different flexural stress at different positions while the flexible OLED display panel is bended, and the bank layer in the area having relatively larger bending degree may be delaminated easily and thereby the encapsulation effect may be decreased.